Early detection is the key to improving melanoma survival: thinner lesions (found earlier) have a much better prognosis than thicker lesions (found later) - in California melanoma survival rates are 98% at 10 years with <0.75mm tumors, but only 48% at 10 years with >3.99mm tumors. Melanoma incidence is increasing rapidly across all thicknesses of melanomas, implying that ad hoc screening efforts are not having an impact on melanoma, which is now the 4th most common cancer among males and 5th among females. We are aware of no formal activities in California to assess the impact and effectiveness of screening interventions for melanoma, yet the US Preventive Services Task Force has been unable to make a recommendation regarding the benefit of screening for melanoma because of insufficient data. We aim to provide data on the effectiveness of skin self examination (SSE). We are focusing on SSE because population-based physician-initiated melanoma screening has been shown to be impractical and probably ineffective. SSE offers an opportunity to find melanomas early, with minimal cost, and indications are that well-informed individuals can find melanomas just as easily as non- specialist physicians. A randomized intervention study of SSE has never been conducted. We have successfully piloted the SSE and have obtained data assessing the efficacy of SSE that strongly suggest SSE can be readily adopted on a population basis. However, we need to demonstrate that SSE can accurately identify problem lesions, and that appropriate care will subsequently be sought. We will conduct a study of the accuracy (sensitivity and specificity) of SSE in detecting lesions in members of the Kaiser Permanente Southern California (KPSC) Health Care system. We will compare an individual's assessment of their own nevi (using SSE) to clinical evidence of precancerous lesions using full body skin exams and whole body digital imaging for both prevalent conditions, and new and changing lesions at 18 months, documenting the occurrence of timely follow-up care. This approach has many advantages: (1) we will examine SSE's ability to find BOTH prevalent and incident conditions, comparing SSE use to a gold standard (physician verification using state-of-the-art digital imaging), not accomplished to date;(2) loss to follow-up will be minimized (or completely avoided) using electronic medical records data from KPSC;(3) should it be shown to be accurate, the SSE could be immediately tested in a randomized controlled trial in the KPSC population, and then adopted by KPSC for the prevention of melanoma and NMSC. Southern California KPSC is a population of millions, among those at highest melanoma risk in the world.